Question 1

What is an ADU (Accessory Dwelling Unit)?

Accepted Answer

An ADU (Accessory Dwelling Unit) is a secondary housing unit on a single-family residential lot. Also called a granny flat, backyard cottage, in-law suite, casita, or garage conversion. ADUs can generate rental income of $1,200–$2,500/month and increase property value by $120K–$280K.

Question 2

Do I need permit-ready plans for an ADU?

Accepted Answer

Yes — to build an ADU legally, you need permit-ready (PE-stamped) engineering plans accepted by your local building department. QuiPlans provides PE-stamped structural drawings prepared by licensed Professional Engineers in 25 U.S. states, including architectural, structural, and MEP engineering plans.

Question 3

How much does it cost to build an ADU?

Accepted Answer

ADU construction costs typically range from $80,000 to $300,000+ depending on size, location, and finishes. A studio ADU (400 sq ft) typically costs $80K–$140K. A 1-bedroom ADU (550 sq ft) costs $100K–$175K. A 2-bedroom ADU (750 sq ft) typically costs $150K–$250K. Use our ADU cost calculator for a detailed estimate.

Question 4

How long does it take to get permit-ready ADU plans?

Accepted Answer

QuiPlans delivers PE-stamped permit-ready plans in 10–14 business days. Instant downloadable architectural concept drawings are available immediately after purchase. The complete permit package including site plan, drainage, and grading takes 3–4 weeks.

Question 5

Which states do QuiPlans engineers work in?

Accepted Answer

QuiPlans licensed engineers cover 25 U.S. states: FL, TX, GA, NC, VA, MD, SC, TN, OH, MI, PA, NJ, NY, CT, MA, RI, ME, AZ, NV, CO, CA, LA, OK, NM, and DC. We are expanding to additional states.

Question 6

What's the difference between a concept plan and permit-ready plans?

Accepted Answer

A concept plan is an architectural drawing set for early planning, contractor quotes, and HOA submissions — it cannot be submitted for a building permit. PE-Stamped permit-ready plans are signed and sealed by a licensed Professional Engineer and include architectural, structural, and MEP drawings — everything your building department needs to issue a permit.

Question 7

Can I customize an ADU floor plan?

Accepted Answer

Yes. All 31 QuiPlans floor plans can be customized to your needs — modify bedroom count, bathroom layout, exterior style, square footage, and more. Customization pricing is based on square footage and complexity. Contact us for a custom quote.

Question 8

How much rental income can an ADU generate?

Accepted Answer

ADU rental income varies by location and size. A studio ADU typically generates $1,200–$1,800/month. A 1-bedroom ADU generates $1,400–$2,200/month. A 2-bedroom ADU generates $1,800–$2,500/month. In high-demand markets like California, ADUs can generate $2,500–$3,500/month.

Question 9

Do I need a feasibility study before buying plans?

Accepted Answer

If you're unsure whether your lot can support an ADU — due to zoning, setbacks, lot coverage, or utility constraints — a $349 feasibility study by a licensed engineer will give you a clear go/no-go answer before you invest in plans. The full $349 is credited toward your permit-ready package if you proceed.

Question 10

What is a garage conversion ADU?

Accepted Answer

A garage conversion ADU transforms an existing attached or detached garage into a livable dwelling unit. This is typically the most cost-effective ADU option ($50K–$120K) since the structure already exists. QuiPlans offers garage conversion floor plans and permit-ready engineering for garage conversions in 25 states.

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Build a Backyard Homefor $40,000

Choose Your ADU Plan

Browse 30+ Home & ADU Plans

Ready to Pull Permits?

Build a Backyard Home
for $40,000